3. Implementations of Rural Travel Time Data Collection

This section provides summaries of RTT data
collection implementations. The implementations
described were selected to represent a broad
range of implementation objectives, methods,
and technologies. Emphasis is placed on implementations
that collect travel time data that can be
leveraged in real time. Note that the first
two RTT implementations addressed in this
section (I-35 Minnesota, Duluth to Hinckley;
and I-95 Maine, Portland to Houlton) are described
as detailed case studies, whereas the following
implementations are described more briefly.

3.1 Minnesota DOT's I-35 Temporary Travel
Times System

3.1.1 Background and Planning

Background

In 2012, Minnesota Department of Transportation
(MnDOT) initiated three separate roadway improvement
projects along I-35 from Hinckley to Duluth
that covered approximately 70 miles of rural
highway. The roadway is not a typical weekday
commuter route; I-35 is primarily a recreational
route with high traffic volumes over holidays
and weekends. The peak traffic times occur
mostly on weekends when motorists are traveling
to and from resort areas, and traffic would
be most impacted by construction from May
2012 to October 2012. A detailed account of
the project and its results is provided in
the final report by Athey Creek Consultants
(2013).

Defined need

MnDOT recognized the need to provide accurate
travel times and congestion information to
motorists along the freeway during construction
with minimal latency issues. The system was
to be designed and deployed to aid travelers
in making decisions on whether to travel I-35
or Minnesota State Route 23, an approved alternate
route during construction, as shown in Figure
7. "The purpose of this project is to inform
the traveling public of the travel times through
three major reconstruction projects on I-35
this summer," said Dave Mavec, project engineer.
"The intent is to reduce driver frustration
by displaying the actual driving time it takes
to drive through the corridor. State Route
23 travel times are displayed to encourage
State Route as an alternate route." It was
also important to MnDOT that the public be
involved in providing feedback on the travel
time project.

In addition to several internal criteria,
MnDOT defined the project's intent and purpose
as the following:

Inform travelers of travel times on both
I-35 and the parallel State Route 23 using
roadside static signs with inserted changeable
modules which display real-time travel time
information.

Reduce driver frustration, enhance safety,
and increase traffic efficiency by sufficiently
informing the public about travel times
on the alternate route, thereby encouraging
use of State Route 23 during peak traffic
volume periods.

Inform the traveling public, via a website
link to the MnDOT 511 website, about real-time
travel time information as displayed on
the signs

Adhere to specific accuracy requirements
for each travel time display.

Specifications

The travel time system was to be automated
and used temporarily during the I-35 construction
projects. MnDOT created a performance specification
allowing the contractors to pursue the travel
time system that met the project objectives
so long as maintenance and upkeep of the system
were minimal. Among other criteria, the specifications
included the following:

The system shall have sufficient traffic detection devices to detect traffic speeds
and by the use of an algorithm compute and
communicate estimated travel time to the
signs at the locations in the plan.

All traffic sensors for this project shall
be nonintrusive to the pavement except as
permitted by the Engineer.

The system message shall update at least
every 5 minutes. The system shall self-test
for communication or sensor failures. All
sensors shall be of a type whose accuracy
and latency are not degraded by inclement
weather or degraded visibility conditions
including precipitation, fog, darkness,
excessive dust, and road debris and have
sufficient power capability to run 24 hours
per day/7days per week for the duration
of the project.

The contractor shall create a website
which is accessible from a link on the MnDOT
511 website which displays a map-based representation
of the project showing the sign locations
and the near real-time travel times as shown
on the actual signs (deployed in the field).

3.1.2 Implementation and Management

Contract requirements

MnDOT hired a contractor through its Design-Build
process to implement a temporary standalone
travel time project throughout the I-35 work
zones and on an arterial highway, State Route
23. The system included deployment of seven
roadside static signs along I-35 with inserted
changeable modules that displayed travel times
to the motorists in real-time, as shown in
Figure 8.

The system was required to have sufficient
traffic detection devices (sensors) to detect
traffic speeds and, by the use of an algorithm,
compute and communicate estimated travel times.
The quantity and location of sensors were
not specified in the plans and were to be
tailored to the site by the contractor. Sensors
were required to be relocated when construction
stages changed. The contractor, Renaissance
Technologies, Inc. (RTI), deployed 12 radar
sensors to collect travel time information.
The traffic data collected was archived in
an .zxml format and ultimately transferred
to MnDOT ownership (Athey Creek Consultants,
2013). Updates to travel time information
were required to occur at least every 5 minutes.
The accuracy and latency values were determined
by reviewing values used by MnDOT for travel
time displays in the Metro area, calculations
based on a percentage of travel times between
signs at normal speeds, and a maximum deviation
thought to be acceptable to the public. After
this analysis, MnDOT estimated that the public
would not likely accept more than a 15 minute
deviation at any one sign. The final accuracy
and latency deviation from the displayed travel
time values were determined using engineering
judgment for each sign location.

Dissemination

RTI's flagship software, TrafAlert™,
was used to communicate travel time information
to the public via eight DMS, seven roadside
static signs, and an online travel time map.
Messages displayed on the seven roadside static
signs are depicted in Figure 9. The TrafAlert™
software enabled total control of roadside
signs and sensors from a central location.
Because this work zone was outside of the
installed communications devices of the MnDOT
TMC's central dispatch, the I-35 system operated
independently of the TMC and was not integrated
into any other MnDOT system.

Travel time accuracy was assessed by MnDOT
using floating car runs to compare travel
time estimates to actual drive times. The
assessment found that 95 percent of travel
times were within the allowable accuracy range
and that, among the 5 percent that were out
of range, more than 85 percent of these instances
occurred during or shortly after periods of
congestion began. MnDOT also conducted online
surveys to assess travelers' reactions to
the travel time system. The surveys found
that nearly all respondents who traveled the
designated route noticed the travel time information.
Respondents felt that the information helped
them make route and other planning decisions,
set expectations, and reduce stress.

3.1.3 Lessons Learned

Overall, MnDOT deems the project as a success
which benefited travelers throughout the summer
travel season. Feedback obtained through a
public survey was generally positive, and
respondents appreciated having information
that prepared them for congestion in the work
zone and assisted them in making decisions
about taking alternate routes.

Through comments provided by MnDOT staff
and the contractor, MnDOT has indicated they
may provide additional system specifications
to contractors in the future in order to enhance
travel time data output accuracy and minimize
latency. MnDOT indicated that project costs
were much more affordable compared to implementing
a permanent system.

An extensive set of lessons learned by MnDOT
and the project contractor are provided in
the project final report (Athey Creek Consultants,
2013) and select lessons learned are summarized
below:

The "best-value procurement" method was
effective in helping MnDOT to select a qualified
contractor. MnDOT has a manual that describes
the best-value procurement method (MnDOT
Office of Construction and Innovative Contracting,
2012).

Language used in bid documents should
avoid unnecessarily restrictive requirements
and all terms should be unambiguous.

MnDOT provided specifications to the
contractor that emphasized performance outcomes
rather than detailed design specifications.
This gave the contractor more ability to
innovate and adapt to create the best possible
system. This approach also transferred risk
and liability to the contractor rather than
to MnDOT. However, more detailed design
specifications for some system aspects (e.g.,
sensor spacing and detection capabilities)
could have potentially led to improved system
performance. The project staff acknowledges
that there are tradeoffs between cost and
system performance.

Contractors should be required to provide
a detailed quality control plan that outlines
how they will set up and test the system
and monitor and correct issues.

The methods and criteria that the transportation
agency plans to use to verify travel time
data accuracy should be specified to contractors
during the bid process so that they can
assess the validity of the method and the
potential risks of not meeting performance
criteria. The verification method should
include multiple assessments at different
times and days.

The contract initially stated that monetary
deductions would be assessed against the
contractor if any part of the system was
not functional, but was later revised to
state that deductions would only occur if
the nonfunctional component adversely affected
travel times. This revised language provides
contractors with an incentive to design
a robust system and avoid penalization for
inconsequential issues.

A project website with a construction
map was created by the contractor and was
available via a link on the MnDOT 511 website.
The link was difficult to find, however,
and true integration of the site within
the MnDOT website could have been more effective.

It would have been useful to provide
ITS system training to work zone supervisors
prior to developing bid documents so that
they could become more familiar with the
candidate technologies.

Public feedback about the travel time
project was generally positive, although
northbound travelers would have liked to
receive the travel time information before
passing an exit to a viable alternate route.
This emphasizes the need to provide motorists
with travel time information prior to decision
points to allow them to make effective routing
choices.

3.2.1 Background and Planning

Background

During 2008 and 2009, the State of Maine
updated its VSL signs system (see Figure 10)
on Interstate 95, Interstate 295, and surrounding
arterial routes. The State's intention was
not just to capture data related to user delay
and vary speed limits to make them appropriate
for conditions, but ultimately to provide
travel time information to motorists. The
Maine Department of Transportation (MaineDOT)
currently displays variable speed limits across
the I-95 corridor and provides situational
alerts through the 511 system. The system
measures and displays speeds to enhance real-time
information relayed to motorists.

Initially, the State's goal was to improve
incident notification information for all
highway incidents and weather events, control
speeds, and improve the State's 511 System
mapping capabilities for the public. The Maine
511 Travel Information Service is designed
to help commuters and travelers access information
regarding weather-related road conditions,
construction zones, and congestion areas,
via either the 511 website (www.511maine.gov)
as shown in Figure 11 or phone, 24 hours a
day and 7 days a week. The 511 website hosts
a traveler information map containing information
on speeds along the corridor. While motorists
aren't explicitly given travel time information,
in a rural setting the posted variable speed
limit may help to identify areas where delays
exist and implicitly advise motorists to consider
other routes.

Data Collection

The addition of the radar units on the back
of the VSL signs allows MaineDOT to measure
average Interstate segment speeds, which can
be used to detect delays and estimate travel
times to key junction points. The agency uses
this information to manage the corridor and
reduce impacts to travel caused by incidents
or weather, with information being updated
to the traveler information map.

3.2.2 Implementation and Management

Sensor Locations

The systems are installed at the end of interchange
on-ramps on both the northbound and southbound
side of I-95 and I-295 and controlled via cell
modem from MaineDOT's central radio room. There
are 75 signs installed from Portland to Houlton
covering a distance of approximate 260 miles.
The distance between the interchanges ranges
from 2 miles to 10 miles apart. The VSL signs
allow the Department to measure average Interstate
segment speeds, which can be used to detect
delays and allow motorists to estimate travel
durations to key junction points. MaineDOT is
also using Bluetooth technology through TrafficCast
to monitor real-time travel data for several
other routes.

System Architecture and Processes

The VSL system is not part of an integrated
system, but it uses a tiered approach that
involves the radar, camera, and dispatcher
information to verify incidents on the corridor
and reinforce decisions for the route. Analysis
of the data is automated, but it involves
direct review, analysis, and decision making
by MaineDOT dispatchers. MaineDOT built this
into their process to give a sense of ownership
to the dispatchers. The dispatchers have three
main roles: 1) monitor the two-way radio communications;
2) address public inquiries; and 3) maintain
the data entry of the information posted on
the 511 website and traveler information map.
The dispatchers oversee the communications
to the signs. This is accomplished through
the use of a cellular modem, which is sampled
every 15 minutes. Speed and occupancy data
are sent to a server and processed through
an algorithm analysis. A threshold speed of
40 mph initiates an alert that is emailed
to a dispatcher. The dispatcher reviews the
data, which are displayed in a spreadsheet.
Based on the data presented, the dispatcher
will program the VSL sign(s) to reflect an
appropriate speed for the current road conditions.
If available, the dispatcher will use a camera
feed to verify the roadway condition, and
issue a situational alert for public and operations
posting.

3.2.3 Future Considerations

Mobile Applications

MaineDOT is considering evaluating mobile
applications used by smartphones to collect
traveler information that the user agrees
to send. One example of a social application
is Waze, a community-based traffic and navigation
application for real-time traffic and road
information. The data from the Waze application
may be used in the future to build value on
top of data currently available to MaineDOT
and can supplement information being collected
by the agency. This information may eventually
help to explicitly communicate travel times
to motorists who are without access to mobile
devices. To consider integrating mobile applications
into the traffic management process, MaineDOT
is working on a request for information (RFI)
to solicit other application vendors to come
forward and be evaluated.

Costs

Costs for this basic but informative way
to share travel information are much less
than deployment of DMS and associated hardware,
software, and technology packages. The total
MaineDOT VSL project cost was $776,849.54.
The replacement cost for a VSL sign is estimated
at approximately $10,000. To add a radar unit
to each sign costs approximately $500 and
each camera costs approximately $1,500. The
combined cost for cameras and radar units
was approximately $66,000. In comparison,
deploying this type of system costs approximately
one-tenth of traditional travel time communication
devices such as DMS.

3.3 Various Statewide Routes, Wisconsin

Wisconsin DOT (WisDOT) has implemented travel
time data collection systems on rural roads
as part of its Traffic Operations Implementation
Plan (TOIP), which guides efforts in transportation
planning and improvement, and allows ITS to
be implemented in major roadway projects at
a cost that is considered incidental to the
project (i.e., less than 10 percent of project
cost). The TOIP encourages ITS deployment to
be considered in the construction process, to
be used to mitigate construction-related congestion,
and helps to distribute ITS deployments where
they are most needed.

On rural freeways, WisDOT captures travel
time data using sidefire microwave detectors.
RTT coverage is provided in the vicinity of
the I-90/I-94 split near Tomah, WI (see Figure
12) on the I-94 corridor between Milwaukee
and Madison (see Figure 12), and a portion
of US-41 between Milwaukee and Green Bay.
WisDOT has been implementing these travel
time deployments for about 7 years. Prior
to sidefire radar, WisDOT used loop detectors
as its primary source of travel time data,
then shifted to microwave detection. Microwave
detection was preferred over loop detectors
and eventually became standard practice because
it was easier to maintain and replace, with
the particular benefit of not requiring lane
closures and invasive pavement work.

WisDOT experience shows that rural travel
times vary infrequently unless there is a
traffic incident. The RTT system, however,
is not intended specifically for use as an
incident detection system and does not include
any features for automatic incident detection;
WisDOT generally learns of incidents first
from police reports.

WisDOT provides DMS showing travel times
on some rural routes. In a non-scientific
survey, about 80 percent of drivers stated
a preference for messages that show both travel
time and distances to destinations. In rural
areas, travel time sign destinations may be
relatively far away and destination names
might not be meaningful in and of themselves
to drivers, so providing distance allows drivers
who are unfamiliar with the area to calculate
travel times for themselves.

In the future, WisDOT anticipates that travel
time data collection technologies may transition
to Bluetooth probe technologies due to the
lower cost of installation and maintenance,
or the agency may opt to purchase third-party
travel time data. WisDOT is also interested
in the possibilities of connected vehicle
technology for travel time data. It is possible
that the future role of WisDOT and other DOTs
will not be in collecting travel time data
themselves, but validating data from third-party
sources.

3.4 I-45 from Houston to Dallas, Texas

The I-45 corridor is a rural Interstate of
approximately 230 miles that connects Houston
and Dallas and serves as a hurricane evacuation
route. In recent years, major hurricanes threatened
the Gulf Coast and have brought attention
to the need for effective hurricane evacuation
management. Transportation officials needed
the ability to monitor traffic conditions
along the evacuation route and to determine
whether to deploy contraflow (Texas Transportation
Researcher, June 2010).

In 2009 Bluetooth detectors were installed
along 225 miles of I-45 to collect the necessary
traffic information. Two examples of pole-mounted
Bluetooth units are shown in Figure 13. Detector
spacing ranges from 5 miles to 20 miles, but
sensors are typically between 5 and 8 miles
apart. Bluetooth was selected for use primarily
because it was significantly less expensive
than the toll tag reader technology that has
been used in earlier implementations. Before
the implementation began, Houston TranStar,
a partnership of government agencies responsible
for providing transportation and emergency
management services to the Greater Houston
Region, conducted feasibility testing to ensure
that Bluetooth captured sufficient data and
reported accurate travel times. Testing showed
that Bluetooth performed comparably to Houston's
more established toll tag reader technology
(Puckett, 2011).

In addition to aiding with evacuation planning,
the travel time system is intended to provide
useful information to motorists and TranStar
staff regarding current traffic conditions.
Color coded real-time travel times are displayed
on a map on the Houston TranStar website (see
Figure 14).

3.5 Various Routes in Oregon, Frontier Travel
Time Project

In 2000, the Frontier Project Technical Advisory
Committee (TAC), which includes representatives
from eight State DOTs, selected an RTT estimation
system for demonstration on rural highways
near the Oregon coast (Wright, Shi, &
Lee, 2005). Congestion and incidents are common
on this corridor, and the TAC intended for
the demonstration project to be capable of
providing travel times and incident information
to Oregon DOT (ODOT) and to motorists.

The TAC distributed system requirements to
interested vendors and vetted bids based on
price, previous success with travel time deployments,
and timeliness. The TAC chose an infrared
ALPR technology. The system read license plates,
encrypted the license plate numbers, and sent
them via telephone communications to a central
server, where vehicle matches were made and
travel times were calculated. The entire travel
time system consisted of a total of six license
plate recognition cameras mounted on cantilevers
above the road. Each installation consists
of two cameras, one for each direction. One
road segment was 3.15 miles long and the other
road segment was 22.25 miles long. The TAC
cooperated closely with the vendor to ensure
that the system was installed as specified.

The system operated as intended for the first
2 months in 2001, but then a series of software
and equipment failures ended the initial effort,
and the system remained dysfunctional until
2004. The most significant problem was a faulty
power supply module, which was not replaced
by the vendor for almost 1 year. Once the
replacement part was available, it took another
year for ODOT staff to fully repair the system
because there was a significant backlog of
maintenance work elsewhere, and the travel
time system was considered non-critical to
safe operation of the roadway network.

Upon restoration of the system, the quality
of the system's data was evaluated. Analyses
showed that when the system was functional,
it provided accurate travel times, though
an insufficient amount of data were available
under congested conditions to evaluate system
accuracy when traffic is heavy. Segment length
had a significant effect on vehicle match
rates: for the long 22-mile segment, match
rates were under 5 percent of traffic, whereas
for the short 3-mile segment, match rates
were above 15 percent. The system also could
be used for incident detection, but ODOT found
that cell phone calls from motorists and other
communication means were generally faster
and more reliable. Despite this success, the
system was discontinued due to ongoing operational
and maintenance issues; ODOT was not willing
to rely on the data or disseminate it given
that the system was prone to failure.

Lessons learned in this demonstration project
include:

Maintenance of ITS devices is particularly
burdensome to rural transportation districts,
which may have less staff covering a wider
area than urban districts and fewer maintenance
funds

Travel time systems must be operationally
reliable to be used effectively

Sufficient staff, equipment, and funding
should be available for system maintenance

There are risks in deploying a first-of-its-kind
project

Segment length and congested conditions
have an effect on data reliability

3.6 State Route 520 in Orange County, FL

The Orlando-Orange County Expressway Authority
(OOCEA) manages one DMS, located in the eastern
part of Orange County, between Orlando and
the Atlantic coast. The sign was installed
in 2008 on northbound SR-520, about 0.5 miles
before reaching SR-528. This sign is in a
largely undeveloped, rural area.

Figure 15. Orange County Road NetworkSource: Google Maps

This DMS was originally intended to assist
with coastal evacuations: in such scenarios,
the SR-520 northbound to SR-528 westbound
route would be heavily utilized (see Figure
15). However, at this junction drivers headed
toward Orlando have the choice of either remaining
on SR-520 or switching to SR-528; both routes
are viable options to reach much of the Orlando
area. To aid drivers, travel times for westbound
SR-528 are shown on this DMS. SR-528 is a
toll road that is heavily used by commuters
to Orlando and travelers headed to or from
Orlando International Airport. Although travel
times are not shown for SR-520, drivers can
use the SR-528 travel time to help determine
which route would be best for them. For example,
an unusually long travel time on SR-528 might
suggest that SR-520 would be a faster route.
As an added incentive, there is no toll on
SR-520.

Travel times are calculated from vehicles'
on-board toll transponders, used for toll
collection on SR-528. Travel times are calculated
each minute. However, 10 vehicles matched
between 2 locations are needed to develop
an average. When there are fewer than 10 matches
every minute, the sign displays the travel
time as calculated from the most recent 10
reads.

The sign is normally formatted as displayed
in Figure 16. The destinations displayed are
always Orlando International Airport and SR-417.
However, if the travel time to either of these
destinations is a certain percentage (e.g.,
50-100 percent) above the normal or expected
travel time, there is instead another display.
(Expected travel time is calculated from the
mean travel time at that time of day, as recorded
over the past 4 weeks.) The banner "TRAVEL
TIME VIA SR 528 TO" is then replaced by "TRAVEL
TIME ALERT." The word "ALERT" flashes, as
do the destination(s) for which the travel
time is elevated. The travel times also flash.
In the case of a travel time alert, the DMS
is two-phased and alternates with an incident-related
message (i.e. CRASH AHEAD). Although travel
times are not shown for the alternate route
(SR-520), drivers can use the SR-528 traffic
conditions as a basis for route choice. The
sign operates 24 hours a day.

3.7 I-90, Snoqualmie Pass in Washington

I-90 is a major freeway connecting Seattle
with inland Washington State, though much
of the route is situated in a rural setting.
About 50 miles from Seattle, I-90 traverses
Snoqualmie Pass, a mountain pass at 3,000
feet elevation. According to Washington State
DOT (WSDOT), the Pass carries more than 10
million travelers per year. Due to the pass's
unique climate, it receives huge amounts of
precipitation, including an average of more
than 400 inches of snow per year. The extreme
weather conditions can make the Pass unsafe
to drive, occasionally required road closures
due to unsafe conditions or avalanche risk.
In recent winters, crash-related closure of
the Pass has averaged fewer than 20 hours
per winter. Avalanche closures are more varied,
ranging from fewer than 10 hours in 2009-2010
up to more than 100 hours in 2007-2008 and
2008-2009. In addition to winter weather issues,
Snoqualmie Pass can experience congestion
on summer weekends and holidays, and a long-term
construction project is expected to add to
delays (Rick Gifford, personal communication,
February 2013).

Due to unpredictable mountain pass conditions,
in 2011 WSDOT began providing information
to drivers on its website, smartphone app,
and on travel time signs on I-90. The website
(www.wsdot.com/traffic/passes/snoqualmie/)
provides travel times for the 74-mile stretch
of mountainous terrain as well as a color
coded traffic map with live traffic cameras
(see Figure 17), and additional information
on current weather and road conditions, forecast,
and travel restrictions.

Three travel time signs (one eastbound and
two westbound) provide drivers with travel
times and distances to the Pass (see Figure
18). The travel times are currently calculated
using data from the third-party data provider
INRIX. However, WSDOT is currently installing
nearly 30 radar detectors along the 74 miles
surrounding the Pass that will ultimately
be used to calculate travel times in place
of the INRIX data.

Advantages of radar over INRIX data for WSDOT
include data ownership, a more compatible
costing structure (i.e., easier to obtain
funding for purchases than ongoing payments),
and overall cost savings (Rick Gifford, personal
communication, February 2013). The combination
of radar and probe data provides WSDOT with
more precise speed data, and adds traffic
volume data.

According to WSDOT, "This work was funded
by $800,000 of electrical preservation funds,
as well as $500,000 from the I-90 Snoqualmie
Pass East corridor project. The $1.3 million
project replaces a 20-year-old communications
system and includes the online [traffic] flow
maps, travel time signs that were activated
earlier this summer, and provides real-time
information to drivers and our Traffic Management
Center."